The Straight Dope

Go Back   Straight Dope Message Board > Main > General Questions

Reply
 
Thread Tools Display Modes
  #1  
Old 04-22-2011, 07:09 AM
madrabbitwoman madrabbitwoman is offline
Member
 
Join Date: Nov 2007
Location: Aussie
Posts: 1,646
Do most male children grow up to be taller than their mothers?

This question is from a friend (as the result of a very weird conversation). She believes that it would be natural for boys to always end up taller than their mother. I'm not so sure so I want to see what the teeming many can come up with.
Reply With Quote
  #2  
Old 04-22-2011, 07:29 AM
Der Trihs Der Trihs is offline
Member
 
Join Date: Aug 2005
Location: California
Posts: 35,981
Males on average grow taller than females. Therefore, sons are normally going to be taller than their mothers, or most other women for that matter.
Reply With Quote
  #3  
Old 04-22-2011, 07:53 AM
Wendell Wagner Wendell Wagner is offline
Charter Member
 
Join Date: Jul 1999
Location: Greenbelt, Maryland
Posts: 11,552
I've been told that a good way of predicting a child's height is the following:

Let the father's height be x and the mother's height be y (in inches).

For a boy, the most likely height is (x + y + 5)/2.

For a girl, the most likely height is (x + y - 5)/2.

This is because adult men are about five inches taller than adult women (and some other facts about the inheritance of height which I won't go into).

You can see then that the most likely height for a son is (x + y)/2 + 5/2. Since the average difference between the mother's and the father's height is that the father is five inches taller, this means that on average the son will be taller than the mother. Of course, this doesn't mean that sons will always be taller than their mothers, just that on average they will. Indeed, there are (somewhat unlikely) circumstances where you can even predict that the son will probably be shorter than their mother. Suppose the mother is nine inches taller than the father (so x = y - 9). Then the formula predicts that the most likely height for the son is ((y - 9) + y + 5)/2, which equals (2y - 4)/2, which equals y - 2. So if the mother is considerably taller than the father, the son will probably be shorter than his mother. But, once again, this is only the most likely height, not what it will always be.

Last edited by Wendell Wagner; 04-22-2011 at 07:54 AM..
Reply With Quote
  #4  
Old 04-22-2011, 08:14 AM
Blake Blake is offline
Member
 
Join Date: Mar 2001
Posts: 10,101
Quote:
Originally Posted by Wendell Wagner View Post
You can see then that the most likely height for a son is (x + y)/2 + 5/2.
Or in simpler form, males will on average be ~3 inches taller than the average height of their parents.
Reply With Quote
  #5  
Old 04-22-2011, 09:19 AM
Wendell Wagner Wendell Wagner is offline
Charter Member
 
Join Date: Jul 1999
Location: Greenbelt, Maryland
Posts: 11,552
Well, two and a half, but you get the point.
Reply With Quote
  #6  
Old 04-22-2011, 09:53 AM
bump bump is online now
Guest
 
Join Date: Jun 2000
Quote:
Originally Posted by Blake View Post
Or in simpler form, males will on average be ~3 inches taller than the average height of their parents.
And the formula doesn't imply that there's any specific height gain from having a tall mother or father.

I think the formula may be a good baseline, but not 100% accurate. My brother and I are both between 6'0" and 6'1", and our dad's 6'3" and mom's 4'11", so by the formula, we should both be 5'9" and a half-inch.

Also, according to the formula, my son ought to be 6'3" and a half-inch- our heights average to 6'1". I don't know if that's the case- she's freaky tall for her side of the family (dwarfs all but the tallest men, including her grandparents, parents and sibling), while I'm tall for my mother's side, but about average for my father's side.

I suspect he'll end up at least my height, and probably closer to hers, but I don't know if he'll end up an inch and a half taller than her, and 3 inches taller than me.
Reply With Quote
  #7  
Old 04-22-2011, 10:08 AM
Marley23 Marley23 is online now
I Am the One Who Bans
Moderator
 
Join Date: Apr 2002
Location: New York
Posts: 75,182
Quote:
Originally Posted by bump View Post
I think the formula may be a good baseline, but not 100% accurate.
Of course it's not 100 percent accurate. It's based on averages. I'm almost exactly the average of my parents' heights- if the formula were 100% accurate, I'd be about two inches taller.

There's probably more recent data by now, but this 2002 CDC report [PDF warning] says the average adult U.S. male is 5'9.6" and the average woman is 5'4.2." (They did stop collecting data when the subjects were 19.) That makes it pretty obvious most guys are going to be taller than their mothers. If you apply the formula posted upthread and assume two average-height people have one child of each gender who is also average-height, you get a son who will be 5'9.2" and a daughter who is 5'4.4." That is, you'd have a son who is a little shorter than his father but much taller than his mother and sister, and a daughter who is much shorter than her father and her brother and just a little taller than her mother.
Reply With Quote
  #8  
Old 04-22-2011, 12:33 PM
manila manila is offline
Guest
 
Join Date: Sep 2005
Quote:
Originally Posted by Wendell Wagner View Post
I've been told that a good way of predicting a child's height is the following:

Let the father's height be x and the mother's height be y (in inches).

For a boy, the most likely height is (x + y + 5)/2.

For a girl, the most likely height is (x + y - 5)/2.

This is because adult men are about five inches taller than adult women (and some other facts about the inheritance of height which I won't go into).

...snip.
I also understand that a child is approximately half its adult height when its aged two years. Assuming of course that it hasn't any growth retarding illness at that time.

Does this match any parent's observation?

Last edited by manila; 04-22-2011 at 12:33 PM..
Reply With Quote
  #9  
Old 04-22-2011, 12:36 PM
alphaboi867 alphaboi867 is offline
Member
 
Join Date: Feb 2005
Location: the Keystone State
Posts: 11,038
I'm taller than my father, but not my mother. My brother (who has a different father) is taller than her.
Reply With Quote
  #10  
Old 04-22-2011, 04:33 PM
RickJay RickJay is offline
Charter Jays Fan
Moderator
 
Join Date: Jun 2000
Location: Burlington, Ontario
Posts: 31,250
Quote:
Originally Posted by manila View Post
I also understand that a child is approximately half its adult height when its aged two years. Assuming of course that it hasn't any growth retarding illness at that time.

Does this match any parent's observation?
This may be a general average but individual children vary widely in height and so relying on this will give you some very gimpy results. It would predict my daughter to end up at 6'3" or so, which seems very unlikely.
Reply With Quote
  #11  
Old 04-23-2011, 08:22 PM
elfkin477 elfkin477 is offline
Member
 
Join Date: Apr 2001
Location: NH
Posts: 19,261
Quote:
Originally Posted by Wendell Wagner View Post
For a girl, the most likely height is (x + y - 5)/2.
Well, I got screwed then. Mom was 5'4.5" (but is shorter now due to spinal issues) and Dad is 6'2". I'm not quite 5'4" myself. My mom and her sister are both shorter than their mother was too: Grammy was 5'6" and Grampy was 6' but my aunt is only 5'2". I'm not hoping for daughters myself, but I'm interested in seeing how nieces turn out. Hopefully the women in my family won't continue to shrink.

gurujulp, I grew the final inch half way through college but I don't know if I was 19 or 20 at the time.
__________________
Stalk follow me on Twitter
Reply With Quote
  #12  
Old 04-22-2011, 08:06 AM
Blake Blake is offline
Member
 
Join Date: Mar 2001
Posts: 10,101
As Der Trihs says, most male children grow up to be taller than most women. If you pick any random woman and any random male newborn, the child will grow taller than the woman in most cases. So of course most male children grow up to be taller than their mothers.

The other point to bearing mind in regression towards the mean. Basically any child will have the average of their parent's traits. So any child will have the average genetic growth potential of mother and father. Note however that this is genetic potential. There are also a very strong hormonal effects on growth, and males will grow taller than females. As a result males will on average be ~3 inches taller than the mean height of their parents, 3 inches being about the addition that being male adds to genetic potential.

There are only two times you are likely to get an exception. First is if the mother is genetically much taller than the father, at least 4 inches taller. In that case case the male growth advantage may not be sufficient to counter the regression to the mean. The second is if the child is physically prevented from growing due to disease, illness or stress. In those circumstances taller women may very well produce sons shorter than they are.
Reply With Quote
  #13  
Old 04-22-2011, 07:50 AM
Khaki Campbell Khaki Campbell is offline
BANNED
 
Join Date: Jan 2010
Posts: 607
Especially women from the previous generation, because humans get taller and taller.
Reply With Quote
  #14  
Old 04-22-2011, 12:16 PM
Chronos Chronos is offline
Charter Member
 
Join Date: Jan 2000
Location: The Land of Cleves
Posts: 52,830
I'm wondering why anyone would doubt this. It's not like it's any great secret that men in general tend to be significantly taller than women.
Reply With Quote
  #15  
Old 04-22-2011, 12:19 PM
gurujulp gurujulp is offline
Member
 
Join Date: Jun 2008
Location: Oakland, CA
Posts: 1,133
I am .5 inches taller than both parents -
well, I was a decade ago- now they are shrinking...

They were both 5'10" and I am 5'10 1/2"

Last edited by gurujulp; 04-22-2011 at 12:20 PM.. Reason: tallness
Reply With Quote
  #16  
Old 04-22-2011, 01:38 PM
sunstone sunstone is offline
Charter Member
 
Join Date: Jul 2002
Location: Southwest USA
Posts: 1,181
Basically the differential in male and female heights is genetically determined, assuming proper nutrition to all concerned. Height genetically seems to be a trait that is due to several sets of genes that work together to determine height. Some genes make you taller than others. When you get genes from parents, on the average you get some talls and some shorts...but you may get only shorts from Mom and from Dad, or only talls from Mom and Dad...such are the benefits of sexual reproduction.

Males with identical height genes as females will grow taller. This appears to be the case when tall genes are in the presence of testosterone.

Of course, due to many factors such as nutrition and the genes present in populations (think pygmies and Masai), some females are taller than some males, but in all human populations, Males tend to be taller on average than females. There are many exceptions of course.
Reply With Quote
  #17  
Old 04-22-2011, 02:32 PM
BrotherCadfael BrotherCadfael is online now
Guest
 
Join Date: Feb 2003
My daughter is exactly my wife's height. My son is exactly my height.

Both are pissed off about it - my daughter would love to be taller (my wife is not tall), and my son doesn't like being the tallest person around.
Reply With Quote
  #18  
Old 04-22-2011, 02:50 PM
Quintas Quintas is offline
Guest
 
Join Date: Oct 2001
My father and mother are both 5'6" , give or take a 1/4 inch. I'm 6' 2" . How did THAT happen?
Reply With Quote
  #19  
Old 04-22-2011, 03:22 PM
astro astro is offline
Guest
 
Join Date: Jul 1999
Strictly unscientific, but for whatever reason based on the informal observations I've made re parent/child pairs I've seen in my life, it always seemed to me that if the mother being tall had more impact on the son being tall.

Put another way i almost never saw tall mothers with short sons, but did see tall mothers with short daughters.
Reply With Quote
  #20  
Old 04-22-2011, 04:35 PM
picunurse picunurse is offline
Member
 
Join Date: Mar 2003
Location: Seattle
Posts: 11,033
My mother was the same height I am (5'4"). I don't know how tall my father was.
My step-father was 5'2". My first half brother is 6'1", next is 5'8" half sister is 4'10" last half brother 5'2"

One must look beyond just the pervious generation.
Reply With Quote
  #21  
Old 04-23-2011, 08:24 PM
Blake Blake is offline
Member
 
Join Date: Mar 2001
Posts: 10,101
Quote:
Originally Posted by bump View Post
And the formula doesn't imply that there's any specific height gain from having a tall mother or father.
Quote:
Originally Posted by astro View Post
Strictly unscientific, but for whatever reason based on the informal observations I've made re parent/child pairs I've seen in my life, it always seemed to me that if the mother being tall had more impact on the son being tall.

Put another way i almost never saw tall mothers with short sons, but did see tall mothers with short daughters.
I've never seen any evidence that it matters which parent is taller. All these observations can be explained simply because males are hormonally taller.

For a male to be 6' tall he only needs to have "growth genes" that are trivially better than the average population. IOW he genes only needed to make him 2" taller than average. For a woman to be 6' her genes must have been much better than average, since they made her fully 6" taller than average.

So a child of a 6' man will inherit fairly average genes from his father, and if the mother is also of average height the child will also be of average height. In contrast a child of a 6' woman will inherit genes from his mother that will result in him being 6" taller than average. Even if the father is of average height the child will still be 3" taller than the average population.

IOW it doesn't matter which parent is taller. all that matters is how much taller than average the parent is.
Reply With Quote
  #22  
Old 04-23-2011, 10:01 PM
Cub Mistress Cub Mistress is offline
Charter Member
 
Join Date: Nov 2003
Location: Middle Tennessee
Posts: 2,486
this is a good place for a funny story. My grandson is 8 and he is off the chart for height for age. His father, my son, is 5'10' or 5'11', his mother is 6', maybe a little more. When my DIL was looking over my grandson's medical chart she found the following notation explaining my grandson's height: "Father tall for family, mother tall for people" I tease my DIL now about being "tall for people."
Reply With Quote
  #23  
Old 04-22-2011, 06:29 PM
Mosier Mosier is offline
Guest
 
Join Date: Oct 2003
Quote:
Originally Posted by Quintas View Post
My father and mother are both 5'6" , give or take a 1/4 inch. I'm 6' 2" . How did THAT happen?
How tall is your mailman?
Reply With Quote
  #24  
Old 04-23-2011, 05:18 PM
md2000 md2000 is offline
Guest
 
Join Date: Feb 2009
Quote:
Originally Posted by BrotherCadfael View Post
My daughter is exactly my wife's height. My son is exactly my height.

Both are pissed off about it - my daughter would love to be taller (my wife is not tall), and my son doesn't like being the tallest person around.
Ha ha - I saw the opposite, a co-worker who got very upset when her daughter ended up the same size and started wearing all her clothes (serves her right for watching her figure and having good style sense). She was so happy when the girl finally ended up 5 inches taller.

Hmm... I'm shorter than my dad, but taller than my mother. (5'10 vs 6'2" and 5'3").
Reply With Quote
  #25  
Old 04-22-2011, 04:55 PM
BigT BigT is offline
Guest
 
Join Date: Aug 2008
My dad's 5'10", my mom's 5'8", so I should be just under 6' by the formula. I'm 6'3".

My sister is 5'7", but she had knee surgery in sixth grade and had to have her growth plate closed before surgery. According to those tests they do when you are a kid, she was supposed to be 6'. (And it predicted me at 6'2", which is pretty good.)
Reply With Quote
  #26  
Old 04-22-2011, 05:04 PM
astro astro is offline
Guest
 
Join Date: Jul 1999
Quote:
Originally Posted by BigT View Post
My dad's 5'10", my mom's 5'8", so I should be just under 6' by the formula. I'm 6'3".

My sister is 5'7", but she had knee surgery in sixth grade and had to have her growth plate closed before surgery. According to those tests they do when you are a kid, she was supposed to be 6'. (And it predicted me at 6'2", which is pretty good.)
How woud that work unless they operated on both knees?
Reply With Quote
  #27  
Old 04-22-2011, 05:17 PM
Der Trihs Der Trihs is offline
Member
 
Join Date: Aug 2005
Location: California
Posts: 35,981
Quote:
Originally Posted by astro View Post
How woud that work unless they operated on both knees?
Presumably they'd do just that even if the other knee was healthy, in order to prevent one leg ending up longer than the other.
Reply With Quote
  #28  
Old 04-22-2011, 05:42 PM
Renton_lvr Renton_lvr is offline
Guest
 
Join Date: Aug 2000
My mother is 5'5", my father is 5'7" and I am 5'10" (female). Of all my family, only my maternal grandfather can be considered tallish at 6'.
Reply With Quote
  #29  
Old 04-23-2011, 03:29 PM
kittenblue kittenblue is offline
Charter Member
 
Join Date: Apr 2000
Location: Cleveland, Ohio
Posts: 6,407
My ex-husband was/is 5'3", I am 5'4". My son was very worried he was going to be short like his dad and was overjoyed when he sprouted up to 5' 9", which is more in line with the men on my side of the family. Caused no end of problems with his dad, though, since they have had a rather contentious relationship for years...it does not help to have an angry,stronger son towering over you when you are plastered, but that's for another thread.

Oh, and my daughter ended up about 5'2".
Reply With Quote
  #30  
Old 04-23-2011, 08:06 PM
whiterabbit whiterabbit is offline
Guest
 
Join Date: Aug 2000
My mom is 5'9" and my dad was 5'5". My brother is right between the two of them, 5'7" or so.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 12:23 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.

Send questions for Cecil Adams to: cecil@chicagoreader.com

Send comments about this website to: webmaster@straightdope.com

Terms of Use / Privacy Policy

Advertise on the Straight Dope!
(Your direct line to thousands of the smartest, hippest people on the planet, plus a few total dipsticks.)

Publishers - interested in subscribing to the Straight Dope?
Write to: sdsubscriptions@chicagoreader.com.

Copyright 2013 Sun-Times Media, LLC.